Description: (Applicant's Description) The goal of the Biostatistical Core is to provide collaborative support for the design, data transfer and management, analysis and reporting of the three CISRC projects proposed in this grant. Statistical and data management support are necessary to insure the quality of the design, conduct, analysis and reporting of a scientific trial that is a critical component of any collaborative scientific endeavor. With a common experimental design among the three projects, many data management and quality control issues will be shared among projects. By using the shared resource of the Biostatistical Core, all three projects proposed in this grant will benefit from the experience gained in each project. Centrally collected, processed and transferred data between the CIS offices, the Tailored Message Core and the Survey Methods Core will provide integrated functions across the Core elements of the program project and keep individual projects operationally centralized and consistent. Specifically, the Biostatistics Core will provide statistical collaboration in experimental design, sample size, com puter-related questionnaire design, assistance in data collection, processing and retrieval, and analysis of outcome and cost-effectiveness data for the CISRC projects.